This application is related to Disclosure Document number S00949, entitled xe2x80x9cMagnetic Circuit for Horizontal Sputtering Systems Containing Multiple Horizontal Lobes,xe2x80x9d which is dated Mar. 2, 1999.
The present invention concerns a plasma-based sputtering system that sputters material from a target onto a substrate, and in particular concerns the shape of an array of magnets of a magnetron of such a sputtering system.
U.S. Pat. No. 5,248,402 (the xe2x80x9c""402 patentxe2x80x9d) discloses a sputtering system magnetron that includes an array of permanent magnets rotated in proximity to a plane of a target disposed in a vacuum chamber. The shape of the array of magnets resembles a cross-section of an apple. A closed-loop magnetic path established between oppositely poled pairs of magnets of the array is inturned in a stem region proximate to the axis of rotation for the array and has a pair of opposed lobes extending outward from the stem region in a generally semi-circular form. The two lobes lead to and join each other in an indent region opposite the stem region. The maximum distance across the path between the two lobes is about double the minimum distance across the path between the stem region and the indent region.
The present invention includes a sputtering system and associated methods that provide unexpectedly superior deposition uniformity, target utilization, and target erosion uniformity compared to conventional sputtering systems. The superior results are obtained due to the provision of a magnetic path that includes an inturn region and at least two indent regions. By contrast, the magnetic path of the ""402 patent included only one indent region.
An embodiment of the sputtering system includes a vacuum chamber. A rotating magnetron is disposed in the vacuum chamber. A target is positioned between the magnetron and a substrate upon which material from the target is to be deposited. The magnetron includes an array of pairs of oppositely poled permanent magnets. A closed loop magnetic path extends between the pairs of oppositely poled magnets of the array. The magnetic path includes an inturn region proximate to an axis of rotation of the magnetron and at least two (e.g., five) indent regions. As an example, the substrate may be an optical disk, although other types of substrates also may be used.
A method of sputtering using such a sputtering system includes applying electrical power across an inert gas (e.g., argon) in the vacuum chamber so as to form a plasma. Ions generated within the plasma bombard the target, causing material to be dislodged from the target and deposited on the substrate.
These and other aspects of the present invention may be understood by reference to the figures and the following detailed description of the exemplary embodiments.